Zebra finches

[werdnal]

Hi,

Sorry I know this is not wildlife and not British either, so please feel free to move if I have overstepped the forum rules, but just wondered if anyone could shed any light on this "strange" bird behaviour.

Went to a local large shopping centre, where they have a lovely outdoor aviary full of Zebra finches and a few other exotic birds. The finches are all busy nest building. They have been given some fine hay and we watched them flying back and forth carrying this material to their nestboxes. One seemed particularly busy, and as we watched, she/he suddenly pounced on another passing bird. We immediately thought it was a territorial attack; the stange bird having got too close to the nest box, but no - the "attacking" bird, just pucked out a small feather from the other one, and took it to their nest. After a few more trips to pick up other nest material, this same bird pounced on another "victim", stripped a feather, and again took it to the nest. There are loads of birds in the aviary, they have plenty of room and lots of nest material, but I just wondered if this is "normal" behaviour for these, or indeed any other species. I know our native birds will take fleece, feathers and animal hair from hedges and fences, but I have never seen a bird actually pluck another like this!

[Kayleigh]

I dont know about Zebra finches doing this but, I have seen crows plucking sheep they stand on the sheep's back and pluck it..
I thought birds plucked themselves they pluck the breast of themselves this looks like learnt behaviour its less painful to pluck another

[darrenm]

I kept a few Zebra Finches in an aviary when i was younger and also observed the same thing a few times.

They could also be lousy parents at times and would think nothing of robbing another nest box of nest material and covering their own fresh hatched chicks or eggs in it or even burying them with the inevitiable consequences

I wonder if this and other odd behavior may have more to do with them being in captivity and quite a few birds in captivity do display odd behavior and the reason i gave up on keeping captive birds a long time ago and now much prefer to see all bird species in the wild

[STYRBJORN]

This may be reciprocal altruism. Hedge "sparrows" routinely detick each other around the neck and head, areas the birds cannot reach on their own bodies. On the one hand, the ticks reduce reproductive fitness by consuming nutrients and carrying disease; on the other hand, time spent deticking another bird is time lost that could have been spent feeding. If all parties obey the rules, the result is a non-zero-sum game. The cost of carrying the ticks is higher than the cost of deticking other flock members.

A free-loader who is deticked could gain the benefit, and refuse to pay the price of deticking others. It turns out that freeloaders are remembered, ostracised, and the infesting ticks affect the reproductive fitness so that the genes of the freeloader are lost.

Similar behaviour occurs in many social species. Vampire bats, which live in colonies of typically 60-80 individuals, will feed a group member who has failed to find a source, but if an individual fails to reciprocate, it will not be fed by others. A vampire which fails to feed for three successive nights is a dead Dracula!

It may well be that your observed "attacker" will in turn be a "victim". At a small individual cost of one feather each bird nas a ready source of nest material. It would need close observation, and probably marking individuals, but it would make a nice little research project for a doctoral student. Get onto your local Uni!

Note that this is definitely not kin selection, nor is it selection "for the good of the species", one of the sillier ideas about evolution.

Ric.

To add, I am serious about this making a good research project. Reciprocal altriusm is a hot topic in evolutionary psychology. It could be carried out by a sixth form group as a life sciences course. Please, do try to pass this info, and my comments, onto a school or uni. Your own bit of altruism! R.

[King Edward]

It doesn't sound like any kind of altruism to me, reciprocal or otherwise. Mainly because the 'victim' was apparently mugged rather than giving up its feathers voluntarily. It seems more like that this particular bird has just adopted this behaviour as a good way to acquire nesting material, perhaps due to the confined and crowded conditions as suggested by Darren. Wild birds do of course rob food/nesting material from each other, but I haven't heard of this before. You might do better asking the question in a bird keepers forum - it might be just a one-off or it might be widespread in caged birds.

[STYRBJORN]

Originally Posted by King Edward

It doesn't sound like any kind of altruism to me, reciprocal or otherwise. Mainly because the 'victim' was apparently mugged rather than giving up its feathers voluntarily. It seems more like that this particular bird has just adopted this behaviour as a good way to acquire nesting material, perhaps due to the confined and crowded conditions as suggested by Darren. Wild birds do of course rob food/nesting material from each other, but I haven't heard of this before. You might do better asking the question in a bird keepers forum - it might be just a one-off or it might be widespread in caged birds.

All fair points, but the fact that the same behaviour has been observed in other aviaries suggests that it may be quite common. I entirely agree that it may be a stress reaction in a caged population. It would be a mistake to read much into the "apparent mugging," interpreting animal behaviour in human terms. It is certainly worth investigation; if it is a stress reaction, should the population density in caged birds be reduced?

KIng Edward, I can't resist asking this. Do you claim to be of royal blood or merely a potato? I only ask . . .

Ric